The objective of the study was to prove if and how far the natural phenolic compounds in seeds constitute an antioxidant barrier for oils extruded from them and rich in polyenic fatty acids from an n-3 family. The research materials were seeds of flax, camelina, hemp, and echium. Investigated were cold pressed oils, oils with native phenolic compounds removed, and oils enriched with hydrophobic fraction of phenolic compounds that were isolated from de-oiled seeds. Phenolic compounds were hot extracted by 70 % ethanol, and a raw extract was purified in a system of polar and non-polar solvents. The seeds were characterized by differentiated contents of phenolic compounds, the small quantities of which passed into oils during the cold pressure process. The effect of having removed phenolic compounds from oils was an express decrease in their oxidative stability in a Rancimat test and a clear decrease in their antiradical activity towards the DPPH^• radical. The addition of phenolic compounds, isolated from the seeds, improved the oxidative stability and antiradical potential of oils pressed from those seeds. However, the protecting and antiradical power of polyphenols was not high. The effectiveness of the activity of those compounds depended on the kind of oil and dose applied. The highest protection factor (0.52) was obtained in the case of echium oil with the maximal dose of 1500 ppm used. The greatest increase in the antiradical activity towards the DPPH^• radical occurred in the camelina oil.